Double risk, with twin fuel filler caps on a Mini Cooper S Mark II. The report came out strongly against side-mounted fuel-filler caps which stand proud of the bodywork as here, and on the Triumph Herald (right)...

A 1967 Police Investigation By New Scotland Yard

- Summary of a police investigation following a fatal accident.

THE young couple were chatting gaily as they sped homeward in their Mini. It had been a pleasant evening, and as they entered "The Avenue" both failed to notice that they were travelling far too fast. It was just after midnight on a Saturday morning in November 1967.

West along the High Road, and converging with the Mini, came an ordinary Ford Anglia. Keeping a steady pace, the driver passed over the pedestrian crossing outside the bank and entered the junction with The Avenue. Suddenly, out of the corner of his eye, he saw the headlamps of the speeding Mini. He slammed his foot hard on the brake pedal, and waited for the crash.

When it came, it was a glancing blow. The Mini shot out of The Avenue, struck the Annglia's front offside wing and careered on into North Terrace, out of control. The Mini turned on its side and crashed into the back of a parked car. Instantly a flame sprang up from the road 30ft behind the car, shot towards it and engulfed the whole vehicle. The girl died in the fierce fire which followed.

What had caused this extraordinary and traggic blaze?

The inspector on duty at Chelsea Police Station that night was Inspector Sims. He recalls, "When I arrived at the scene, the road was in such a mess that it was difficult to find anything, let alone a cause". After interviewing witnesses the inspector established that the fire had started at least 30ft behind the Mini, and at the same time a traffic patrol officer examining the vehicle discovered that the petrol filler cap was missing. A search was ordered and when daylight came, the cap was recovered lying in the gutter not far from the burnt out shell of the Mini.

Inspector Sims began an investigation into the circumstances of the accident. He found that the petrol filler cap had become dislodged from its seating on the neck of the filler pipe. As a consequence, when the vehicle rolled on to its side the petrol escaped leaving a trail which followed the path of the car. By some means this trail became ignited. and quickly set fire to the contents of the petrol tank. Mr. Sims gave as his opinion that the fire would not have started, had the filler cap remained in position. He suggested that the siting and design of petrol filler caps on all cars should be examined from a safety aspect.

At this point the Metropolitan Police Acccident Research Branch took over and extended the case into a research project. They examined every detail of the damaged vehicle and made a close study of the design and siting of the filler
cap. Having done this they carefully reconstructed the accident leaving no detail unntouched. Their report makes interesting reading, but the most important aspect of the study from a safety point of view was the determination of the exact reason for the dislodgement of the filler cap.

Para. 34 of the report states: "The commparatively slight damage sustained by the filler cap was consistent with it becoming dislodged and falling to the ground rather than being forced off the neck of the filler pipe by contact between the nearside of the vehicle and the road surface. This suggests that the cap may not have been screwed securely to a locked position and that it was dislodged in the colliision." An examination af the filler cap from the burnt-out car had revealed only slight scratchhing of the surface coupled with a short abrasion on the outer knurled edge which had only just penetrated the chromed surface.

The investigators also considered - and rejected - a theory that the cap was rotated and unscrewed on contact with the road. The condition of the cap refuted this, and the evidence of witnesses showed that petrol had begun to spill at the point where the Mini overturned, indicating that the cap was already missing. The driver of the Mini remembered he had filled the tank with petrol earlier on the evening of the accident. He had not checked that the cap had been replaced securely.

The team tried a test with a similar car and found that it was possible to replace the filler cap so that it appeared to be secure, but was in fact only
fractionally held. In this position it was possible to dislodge the cap by impacting the nearside of the car with the observer's body - a sharp but nevertheless gentle blow when compared to the impact of an accident. The fact that the neck of the filler pipe had been "pushed" into the body, and the lip of the pipe had sustained indentation and scoring daamage consistent with heavy direct contact with the road surface was considered final evidence that the cap was already dislodged at the time the pipe neck first struck the road.

Almost anything could have ignited the. spilt petrol; the offside wing of the Ford torn off and dragged along the road throwing out sparks; the side of the Mini itself; or even an electrical fault. The final recommendations resulting from this study by the Accident Research Branch were: "It is recommended that in future car design, petrol filler caps should be recessed within the lines of the bodywork. The most satisfactory arrangement appears to be that in which the filler cap is wholly contained within the body in a recess covered by a separate lockable flap".

The report goes on to urge that filler caps should' at least be recessed or protected by bodywork in some way so that a glancing blow or "roll-over" could never dislodge them. The team also strongly recommend that filler caps should be the locking type to avoid accidental dislodgement in the event of incorrect replaceement, and to prevent children from removing the cap.